As a gift to all Finding Dory and Pixar enthusiasts before the theatrical trailer debuts tomorrow (March 2nd) on The Ellen Show, Yahoo! has given us an in-depth look at the sequel from none other than Director Andrew Stanton! Find out how Stanton's story writing process works, what the most challenging part of writing Finding Dory was, and how Destiny the Whale Shark plays a role in Dory's big-blue epic all after the break!

“Disney doesn’t request those things,” he tells Yahoo Movies, referring to the series of sequels that Pixar has on its upcoming slate. “That was the deal when Disney bought us.

The third movie we ever made [1999’s Toy Story 2] was a sequel, and we learned early on that it’s not worth doing unless it’s good.”

Stanton says the idea for the sequel to Nemo came to him in 2011, after he’d spent nearly a decade thinking the story of a little clownfish’s adventure across the ocean was a happily-ever-after fairytale.
“I never thought there was going to be a sequel,” he remembers, “until one day I went, ‘You know, I worry Dory could get lost again and not find the family she has.’ And I wondered, ‘Where did she come from?'”

Stanton’s new film, which hits theaters on June 17, focuses on the journey of Nemo’s pal, the forgetful fish Dory, voiced again by Ellen DeGeneres. In addition to returning favorite characters from the 2003 film, he also introduces a whole new cast of creatures. The photo above features Destiny, a whale shark voiced by Kaitlin Olson (It’s Always Sunny in Philadelphia). Stanton — who also directed the Pixar movie WALL-E and the live-action adventure John Carter — spoke with Yahoo about that new addition and a whole lot more.

Pixar movies famously take a long to make. What was the timeline on this one?
The summer of 2012 was when I hired a writer, Victoria Strouse. We really started hammering on it. It came really fast, the first draft of it, but I’m a 12-draft guy on average. It takes me a long time to find the right answers. I’m not fast, but also, I don’t give up. I think we nailed everything probably last week. It’s been almost 10 or 11 drafts.

So how different were all the drafts?
It’s not like you write all the drafts and then you make the movie. For me, you get about two years in, writing a lot of drafts, maybe about 6 or 7. And you say, I think these chapters or pages are good enough to start making the film. Then you start to slowly put on the play, in a weird way, and you let that inform all the stuff that’s not working. And then it becomes a race. We’ve been in a race for the last year and a half, to get the parts that still don’t seem to be working rewritten in time for the production to make them.

Did you think about it ever when you were working on 2012’s John Carter?
That’s what happened. I was in post in the last year on John Carter. And when you’re in post, or basically all the story work is done, that’s a different part of your brain than the part that has to just kind of keep everyone on the rails and make sure they’re putting on the play well. That’s when my brain starts to roam. I wrote Nemo while finishing A Bug’s Life. I wrote WALL-E when I was finishing Nemo. I wrote Carter while I was finishing up WALL-E. When you’re working so fast and so hard, it’s an easy time, in a weird way, to just have another ball thrown at you to juggle, because you’re at your peak of juggling things. I’m in the middle of writing two things right now while I’m finishing up Dory.

So let’s talk about this new character, Destiny.
Destiny is somebody from Dory’s past that she didn’t know about. She resides at a conservation park called the Marine Life Institute. There’s quite a cast of new characters and new species in this film. And Destiny is one of a few that we’ll come across who help Dory on her journey to figure out her past and find her parents.

Destiny had an interesting, circuitous route. We originally started with the idea of having there be an adoption story, and Dory having a sister that she was replaced by, and that was originally Destiny. And then the stories morphed and she turned out better to be a friend from Dory’s past that she just didn’t know about.

Destiny had existed in the film for a long time, but has had many different mutations. She’s voiced by Kaitlin Olson, who is an actress I’ve wanted to work with since I saw her — and especially since I heard her — in It’s Always Sunny in Philadelphia. There’s a term, “the camera loves them.“ There’s also people where the microphone loves them, and the animator in you comes out, and you say, “I’d love to animate to that voice.” She has one of those voices.

I imagine you were able to make a lot of changes, especially because Dory has such a bad memory, so you could explain away anything she said in the past pretty easily.
It turns out that having no short-term memory is the worst quality to give a main character ever. It was the bane of our existence and the number one source of our story problems. Because the only way you attach yourself to a main character in a story is because they’re going to change and grow over time. And the only way you can sense that someone is growing is that they have moments of self-reflection. They can literally say, “I was sad about this in act one, but now I’m happy about it.” But when you have someone with short-term memory loss, they have no ability to remember how they were before versus after.

It was a real tough mental game, how to come up with ways to have her express that she felt differently and was maturing over time without her being self-aware of it. It’s not something you have to think about when you work with someone without memory loss; it just comes naturally.

People are already predisposed to liking her, though.
Yeah, but it also became our enemy, because it disguised that there were problems because you were just enjoying her. Then you watched half the movie and you’d think, “I’m not feeling much is going on here. I’m just feeling like she’s just happy or dumb all the time.” Because you didn’t sense any progress. It was really hard.

You knew, and we find out, she’s not as happy as she seems, right?
A lot of my new staff had not worked on the first one. They were a little young. They did not know Dory was a tragic character. I knew she was. No one wanders their adult life across the ocean and is not sad. Her happiness is her armor.

You had to cast a new voice for Nemo because the new movie takes place just six months after the first one. How did you find someone who sounded just like the original Nemo — Alexander Gould, who’s now 21 — when he was just a kid?
What shocked me is that they narrowed it down to 12 kids, and I gotta admit, 8 of the 12 sounded just like him. I actually had too much to choose from. Hayden Rolence [who landed the part] is great. He really just sounds exactly like what Nemo used to sound like. Hayden’s a little bit older. He was 9 by the time were finishing, maybe 10. And it’s okay because Nemo is about 6 months older, and he’s older and wiser just from having crossed the ocean. We just slightly adjusted him to hold his own with his dad. And we actually cast, in a cameo role, the original Nemo [Alexander Gould]. He has a little cameo voice that no one would know because he sounds like a man. But I just felt like I really wanted the Nemo family in the film.

Disney•Pixar's “Finding Dory” reunites everyone’s favorite forgetful blue tang, Dory, with her friends Nemo and Marlin on a search for answers about her past. What can she remember? Who are her parents? And where did she learn to speak Whale?